<html>
<head>
	<meta http-equiv="Content-Type" content="text/html;charset=UTF-8">
	<title>Document</title>
</head>
<body>
	<p>点击下面的按钮，只要i小于5就一直循环代码块。</p>
	<button onclick="myFunction()">点击这里</button>
	<p id="demo"></p>
	<script type="text/javascript">
		function myFunction(){
			var x="",i=0;
			do{
				x=x + "The number is" + i + "<br>";
				i++;
			}
			while (i<5)
			document.getElementById('demo').innerHTML=x;
		}
	</script>
	
</body>
</html>